Chlorophyllin is a semi-synthetic derivative of chlorophyll with antioxidant and antimutagen
properties that controls the enzymes involved in the metabolism of xenobiotics and in the induction of
apoptosis. In this study, we evaluated the effects of chlorophyllin on apoptosis induction, inhibition of cell
proliferation, and gene expression in the human colorectal adenocarcinoma cell line HT29. Chlorophyllin
significantly reduced cell survival after 48 h at 100 μg/mL and after 24 h at 500 or 1,000 μg/mL, respectively
based on both MTT cytotoxicity and cell proliferation kinetics assays. These effects were dose dependent.
Chlorophyllin did not induce apoptosis after 24 h at any concentration. Chlorophyllin downregulated the cell
cycle genes APC and β-catenin (CTNNB1) but did not affect the expression of apoptotic induction genes in the
extrinsic pathway (CASP8) or the intrinsic pathway (CASP9). At the studied concentrations, the inhibitory
effect of chlorophyllin on cell growth was directly related to the regulation of β-catenin gene expression and
not to APC expression, because APC was mutated and inactive. The studied concentrations suggest no potential
for chlorophyllin as an apoptosis inducer based on cytomorphological changes or gene expression changes of
the studied caspases.